The trypanosomal transferrin receptor of trypanosoma brucei : a review

Iron is an essential element for life. Its uptake and utility requires a careful balancing with its toxic capacity, with mammals evolving a safe and bio-viable means of its transport and storage. This transport and storage is also utilized as part of the iron-sequestration arsenal employed by the mammalian hosts’ ‘nutritional immunity’ against parasites. Interestingly, a key element of iron transport, i.e., serum transferrin (Tf), is an essential growth factor for parasitic haemo-protozoans of the genus Trypanosoma. These are major mammalian parasites causing the diseases human African trypanosomosis (HAT) and animal trypanosomosis (AT). Using components of their well-characterized immune evasion system, bloodstream Trypanosoma brucei parasites adapt and scavenge for the mammalian host serum transferrin within their broad host range. The expression site associated genes (ESAG6 and 7) are utilized to construct a heterodimeric serum Tf binding complex which, within its niche in the flagellar pocket, and coupled to the trypanosomes’ fast endocytic rate, allows receptor-mediated acquisition of essential iron from their environment. This review summarizes current knowledge of the trypanosomal transferrin receptor (TfR), with emphasis on the structure and function of the receptor, both in physiological conditions as well as in conditions where the iron supply to parasites is being limited. Potential applications using current knowledge of the parasite receptor are also briefly discussed, primarily focused on potential therapeutic interventions

Clinico-surgical histopathological findings of retinoblastoma cases treated at Kenyatta National Hospital

Background: Retinoblastoma is a primitive embryonal anaplastic tumour composed of undifferentiated retinal elements. It is the most common primary, intraocular malignancy of childhood. After enucleation of the diseased eye, histopathological findings determine the secondary management of the patient. Histopathological spread of the disease is a major prognostic factor on survival of the patient.Objectives: To determine the surgical and histopathological findings of retinoblastoma cases treated at the Kenyatta National Hospital between 1st January 2000 and 31st December 2004 and to correlate gross appearance of globe after enucleation, with histopathological report.Design: Retrospective study.Setting: Kenyatta National Hospital, Kenya’s largest referral and teaching hospital.Subject: One hundred and sixty patients with clinically diagnosed and/or hystologicaly confirmed retinoblastoma.Results: The mean duration of symptoms was ten and a half five months (SD 10.7) median eight months. White reflex was most common symptom in 53.3% of cases, orbital swelling in 39.4%, pain and redness in 15%, squint in 5% and 21.9% had other complaints. On examination, leucocoria was found in 38.8% of patients, enucleated sockets 37%, recurrent mass in the socket in 27.5%, proptosis 22.5%, orbital swelling in 20% while only 1.3% of patients had strabismus. Tumour was found to be grossly confined to the eye ball in 23.0% of operated eyes, clinically outside the eye ball in 14.3% of eyes while 12.4% of operated eyes had thickened optic nerves. Histologically, tumour was confined to the eye ball in 30% of operated eyes while tumour involved the optic nerve but resection margin free of tumour in 3% of eyes. Tumour had extended beyond the resection margin of the optic nerve in 21% of cases. Eleven point four percent had choroidal extension and 24% were reported as having extrascleral spread. The sensitivity of the surgeon’s finding at surgery, when compared to the histological findings was found to be 69.4% while the specificity was 69.6%. The accuracy was 69.5%. Conclusion: There was still late presentation of retinoblastoma in our set up that had been found in studies conducted previously. This was confirmed by the histological findings. There was inadequate documentation of surgical findings, poor record management and a non-comprehensive referral system

Influence of Liquidity on Financial Performance of Insurance Companies in Kenya

Liquidity is the capacity of a company to satisfy its current financial obligations after they fall due.  A firm may incur extra costs if it fails to honor its short term financial obligations. The aim of the study was to determine the influence of liquidity on the financial performance of insurance companies in Kenya. The research applied a correlational research design. A correlational study design is administrated to debate the connection between variables. The target population for this study was the fifty-three insurance companies in Kenya that were operational in 2018. The investigation found that liquidity had an enormous positive effect on financial performance  (Return on assets and return on equity). The study concludes that the greatest threat to liquidity  may occur in an insurance firm during a catastrophe when a large number of claims are received  directly or there could even be prospects of a significantly large claim which insurance companies  should have optimal liquidity for such situations. The review recommends that Insurance firms should monitor liquidity in their firms and adopt corrective actions in instances of high liquidity risk.&nbsp

Breeding management strategies adopted for dairy production under low-input smallholder farming systems of East Africa

Designing and implementing sustainable breeding management programmes is one of the most practical means of improving efficiency in livestock production, particularly in developing countries. The success or failure of an improvement programme hinges strongly on the compatibility of the programme with the objectives of the farming community targeted. This report contributes to a better understanding of the pre-existing breeding management strategies within cattle-keeping communities of the EADD project sites, and will help in the definition of appropriate breeding objectives and the design and implementation of a sustainable breeding programme for the small holder farmers. The farmers in the three countries rear a variety of cattle, classified into two broad categories as exotic and indigenous breed-types. More exotic breed-types are reared in Kenya than in Rwanda and Uganda. Among the exotic breed-types reared, the Holstein-Friesian is most popular in all the countries. The Ayrshire breed-type is also very popular in Kenya. In Uganda, the most common type of cattle are the indigenous Ankole, while in Rwanda, various crosses are popular. There are no written records available on individual animals. The breed-type of animal raised on a farm is significantly influenced by the age and level of education of the head of the household. On average, in households headed by older and more educated people, there are more exotic breed-types of animals reared. These households also live in areas with higher human population density. Farmers implement some form of controlled mating, either to minimize inbreeding, or to seek better mates among the population available. There is also some degree of planned cross-breeding taking place in all the countries. On most farms, animals calved down for the first time when they were above 27 months old, with exotic animals calving at a younger age than indigenous ones. Calving intervals were on average longer in Kenya than in the other countries. Indigenous animals tended to calve for the first time at close to four years of age in Uganda where malnutrition was noted as a key factor requiring to be addressed. More than 10% of the animals on farms within the three countries were culled in a 12 month period with a replacement rate of less than 5%, implying an overall reduction in herd size over time. The most desirable traits in exotic animals raised in all three countries were high milk production and good body conformation. In the indigenous breed-types reared, adaptability was the most important trait in all the countries. An interesting observation was that not all farmers raised the breed-type of animal that they admired most. It was clear that the farmers were knowledgeable to some degree on several aspects related to selective breeding of animals. To effect change in the existing production systems, in addition to availing improved breeding materials at an affordable cost, capacity development using simplified messages targeted to address specific knowledge gaps concerning breed choice, reproduction and selection decisions is required

Expressed centromere specific histone 3 (CENH3) variants in cultivated triploid and wild diploid bananas (Musa spp.)

Open Access JournalCentromeres are specified by a centromere specific histone 3 (CENH3) protein, which exists in a complex environment, interacting with conserved proteins and rapidly evolving satellite DNA sequences. The interactions may become more challenging if multiple CENH3 versions are introduced into the zygote as this can affect post-zygotic mitosis and ultimately sexual reproduction. Here, we characterize CENH3 variant transcripts expressed in cultivated triploid and wild diploid progenitor bananas. We describe both splice- and allelic-[Single Nucleotide Polymorphisms (SNP)] variants and their effects on the predicted secondary structures of protein. Expressed CENH3 transcripts from six banana genotypes were characterized and clustered into three groups (MusaCENH-1A, MusaCENH-1B, and MusaCENH-2) based on similarity. The CENH3 groups differed with SNPs as well as presence of indels resulting from retained and/or skipped exons. The CENH3 transcripts from different banana genotypes were spliced in either 7/6, 5/4 or 6/5 exons/introns. The 7/6 and the 5/4 exon/intron structures were found in both diploids and triploids, however, 7/6 was most predominant. The 6/5 exon/introns structure was a result of failure of the 7/6 to splice correctly. The various transcripts obtained were predicted to encode highly variable N-terminal tails and a relatively conserved C-terminal histone fold domain (HFD). The SNPs were predicted in some cases to affect the secondary structure of protein by lengthening or shorting the affected domains. Sequencing of banana CENH3 transcripts predicts SNP variations that affect amino acid sequences and alternatively spliced transcripts. Most of these changes affect the N-terminal tail of CENH3

Constraints to the use of artificial insemination service and possible solutions

The East Africa Dairy Development (EADD) project is aregional industry development program implemented by a consortium of partners led by Heifer International. It is currently being piloted in 18 sites in Kenya, 8 in Rwanda and 27 in Uganda. The overall goal of the project is to transform the lives of 179,000 families, or about 1 million people, by doubling household dairy income in 10 years through integrated interventions in dairy production, market access and knowledge application. This brief highlights key results of a baseline survey that was carried out with the objective of analyzing the level of preference for and use of artificial insemination (AI) in different project sites, and identifying constraints or problems hindering the optimal use of the service and possible solutions. Details are available in the baseline survey report No. 2

Income Diversification and Intermediation Efficiency: Evidence from Deposit Taking Sacco Societies in Kenya

Research on the relationship between diversification into nontraditional income streams and firm efficiency is scanty. The study seeks to fill the gap by evaluating the relationship between diversification into non interest income and intermediation efficiency of Deposit Taking Sacco Societies (DTSs) in Kenya using a two staged methodology. In the first stage, efficiency scores are generated using Data Envelopment Analysis (DEA), corrected for bias using bootstrapping and used as dependent variable in the fixed effect regression model estimated in the second stage. A balanced panel data of 103 DTSs for a period 2011-2014 was used in the study. The results showed that there exists an inverse relationship between the ratio of noninterest income to total assets and intermediation efficiency. This implied that diversification hurts efficiency. Keywords: Data Envelopment Analysis, Deposit Taking Sacco, Diversification, Intermediation Efficiency, Noninterest income

Computational Analysis of Some Enzymes Involved in Synthesis of Secondary Metabolites in Camellia Sinensis

Tea is one of the most popular beverages worldwide, native to Southeast Asia but currently cultivated in over 35 countries. Studies on its chemical composition reveal that polyphenol metabolites account for 25% to 35% of the total dry weight. Tea has many health benefits owing to secondary metabolites whose level of expression in various tea clones determine tea flavor. The flavor (taste and aroma) and the color of processed tea are used to assess its quality and therefore a detailed analysis of key enzymes involved in the synthesis of secondary metabolites is necessary.  Enzyme PAL (phenylalanine ammonia-lyase) a key enzyme in the phenylpropanoid pathway, playing an important role in the plant development and defense. C4H (cinnamte-4-hydroxylse) an important enzyme in allocating significant amounts of carbon from phenylalanine into the biosynthesis of several metabolites, It maintains activities of the metabolic flux for the operation of the flavanoid pathway. 4CL (4-coumarate: COA ligase) the last enzyme in the general phenylpropanoid pathway that provides precursors for the biosynthesis of a large variety of plant natural products like COA thiol esters of 4-coumarate and other hydroxycinnamate. FLS (flavonol synthase) a key enzyme in flavonol synthesisthat determines the final content of flavonols which play an important role in defense related functions and as potent antioxidants. ANS (anthocyanidin synthase) an enzyme in the biosynthetic pathway to anthocyanin. This study employed a computational approach in the analysis of some of these enzymes to gain insight into the mechanism of synthesis of these bioactive secondary metabolites. Biological databases were used to retrieve amino acid sequences of these key enzymes. Consensus conserved regions in these sequences were identified from highly identical homologs which were useful in modeling the enzymes' three dimensional structures.  A total of 5 key enzymes were analyzed and pockets and cavities in their structures; hence the putative substrate binding sites determined, which gave insight into the enzymes-substrate as well as enzyme cofactor interactions. The preferred orientations of the interactions between substrates and/or co-factors with the enzymes were also simulated through molecular docking.  Analysis of these enzymes revealed unique enzyme structures and very specific substrate and co-factor preference. This analysis offers a platform for optimization of selective expression of these key enzymes through gene expression assays that can potentially alter the quality yield of tea clones. Keywords: camellia sinensis, Secondary metabolites, Conserved regions, Pockets and cavities, Molecular dockin